1. Field of the Invention
The present invention relates to a method for fabricating biochips and, more particularly, to a method for fabricating a plurality of microarrays.
2. Description of the Related Art
Non-covalent bonds such as ionic bond, hydrogen bond and Van der Waals bond in an aqueous solution are generally about 30 to 3000 times as weak as the covalent bond and hardly stable in the aqueous solution. However, macromolecules have so many bonding sites to maintain stable bonding at the room temperature.
The non-covalent bonds contribute to very selective detection and identification of a specific molecule.
Such a molecule that can recognize specific molecules from the other molecules is broadly defined as xe2x80x9creceptorxe2x80x9d, the examples of which include membrane proteins taking charge of signal transmission from the surface of the cell into the cell membrane, oligonucleotides or peptide nucleic acids (PNAs) recognizing the specific sequence of DNA, antibodies involving the immune mechanism, enzymes hydrolyzing metabolites, and the like.
A substance that selectively binds to these receptors is referred to as xe2x80x9cligandxe2x80x9d.
In 1975, Edwin Southern developed the Southern blotting analysis, an approach for detection and identification of a DNA having a specific base sequence. In the Southern blotting analysis, DNA fragments are separated by size in the electrophoresis and moved on a solid substrate such as a nitrocellulose or nylon membrane so that the relative positions of the DNA fragments are maintained.
Subsequently, DNA or RNA having a specific base sequence labeled with a radioactive isotope is placed as a probe into the DNA fragments immobilized on the solid substrate.
The DNA or RNA placed as a probe can bind to the DNA fragments that have a complementary sequence by way of hybridization, which allows identification of the position of the DNA having a specific base sequence.
This approach has been extended to the Northern blotting analysis for analyzing RNA using RNA-DNA hybridization, and the Western blotting analysis for antibody-based protein analysis, all of the blotting analyses are based on the molecular selectivity of biological macromolecules with non-covalent bonds between the receptor and the ligand.
In addition, ELISA (Enzyme-Linked Immunosorbent Assay), which is one of the analysis methods using an antibody like Western blotting analysis, is most widely used in many applications including molecular biology, medical diagnosis, environmental analysis, etc.
These many analysis methods using receptor-ligand bonds are in most cases concerned to the limited number of receptors and ligands.
For example, at least about 1,000,000 DNA molecules of much various structures are available in fabricating a DNA having a sequence of 10 bases from four bases.
Therefore, the experiments concerning the binding reaction between receptors and ligands require repeating procedures with enormous labor, time and resources.
To solve the problem, biochip technologies have been developed, which have the form of microarray in which a plurality of receptors or ligands are two-dimensionally arranged at known positions on the substrate. Such biochips are divided, depending on the type of the biomolecule, into DNA chips using DNA probes, protein chips using proteins such as enzyme or antigen/antibody, and cell chips using cells.
In the fabrication method of microarray for oligonucleotide or peptide chips, the biomolecules can be directly synthesized on the substrate in the chips. However in the most cases, the previously synthesized or purified biomolecules are placed on the substrate as the biologically important molecules such as cDNA or proteins are difficult to be synthesized on the substrate. The method involving direct synthesis of the biomolecules on the substrate provides highly integrated microarrays but requires a complicated fabrication process at high cost. The method of placing the synthesized or purified biomolecules on the substrate typically uses pin-based microspotting technologies, which is disadvantageous in large-scaled production.
It is, therefore, an object of the present invention to provide biochips having a high detecting sensitivity with readiness in fabrication of microarray, and a method for fabricating the same.
To achieve the above object of the present invention, there is provided a method for fabricating biochips including the steps of: (a) immersing fibers wound on solid supports in a solution containing biomolecules to absorb and immobilize the biomolecules onto the fibers; (b) arranging the individual fibers with the biomolecules immobilized thereon, the fibers being separated from each other at a predetermined distance; (c) embedding the arranged fibers with a defined material; (d) cutting the embedded fibers in a direction perpendicular to the lengthwise arrangement direction of the fibers to obtain thin chips; and (e) placing the chips on a substrate and removing the defined material used to embed the fibers, thereby remaining the fiber fragments with the immobilized biomolecules on the substrate.
The fibers are embedded with a wax, ice, or polymer material, and the substrate is a solid substrate.
In another aspect of the present invention, there is provided a biochip including: fibers with biomolecules immobilized thereon; a solid polymer or a frozen aqueous solution filled between the fibers, the fibers being arranged and separated from each other at a predetermined distance.
In another aspect of the present invention, there is provided a biochip including fibers with biomolecules immobilized thereon, the fibers being arranged and separated from each other at a predetermined distance.
Other objects, features and advantages of the present invention will become evident in the detailed description with reference to the following accompanying drawings.